CSIRO Plant Industry scientists and international collaborators have discovered the key to overcoming three major cereal diseases, which in epidemic years cost wheat growers worldwide in excess of AUS$7.8 billion.

In a paper published today in the prestigious journal Science, scientists from CSIRO Plant Industry, the University of Zurich and the International Maize and Wheat Improvement Center have identified a wheat gene sequence which provides protection against leaf rust, stripe rust and powdery mildew.

"Genetic disease resistance is highly desirable in plants as it is more environmentally friendly and profitable than strategies like spraying pesticides," says a senior principal research scientist at CSIRO Plant Industry, Dr Evans Lagudah. "The newly identified resistance gene product — known as Lr34 transporter protein — is the first of its kind to be found in a commercial crop that is capable of delivering broad-spectrum control of multiple pathogens."

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Lr34 has two extremely valuable characteristics. Whereas one gene usually only protects against a single disease for a limited time under commercial production, Lr34 provides long lasting disease resistance and acts against multiple diseases.

"The fungi that cause rust diseases are very adaptable and can rapidly evolve to overcome resistant cereal varieties," Dr Lagudah says. "Scientists and farmers can commonly only respond to a rust outbreak after it has passed, but tests conducted after identifying the Lr34 gene sequence show it has provided partial but constant protection against leaf rust for over 80 years."

Understanding the molecular nature of this type of resistance has important implications for long-term control of rust diseases.

CSIRO Plant Industry's Dr Wolfgang Spielmeyer says an immediate application is the use of the gene sequence to directly select and breed wheat plants that carry the resistance against multiple pathogens.

"The Lr34 gene can now be combined with other disease resistance genes into single cultivars faster and with greater confidence providing even more durable resistance," he says.